1. Field of the Invention
The invention relates generally to systems and methods of optical micro-assemblies. In particular, the invention relates to passive alignment micro-assembled optoelectronic modules forming multichannel parallel optical systems with optical transmitters, including monitoring photodetectors, and optical receivers.
2. Description of the Related Art
With the ever increasing bandwidth requirement of internet network, datacenters face the challenge of transporting enormous amount of data at high speed. Optical interconnects provide a solution to datacenter builders. Depending on the distance of the data transporting requirements, optical interconnects can adopt different approaches. For short reach requirements, i.e., when the transporting distance is less than about 300 meters, multi-channel parallel optical interconnect systems are usually employed. On the other hand, for long reach systems, i.e., when the transporting distance is from a few hundred meters to a few kilometers, single mode serial optical interconnect systems are employed. This invention is related to short reach parallel optical interconnect systems.
In general, an optical communication system is comprised of an optical transmitter end and an optical receiver end. Particularly for parallel optical system, the optical transmitter or receiver end includes a plurality of light emitting or receiving devices for generating or receiving light signals and encoding or decoding electrical/optical signals, a plurality of light coupling elements (such as lenses, mirrors, gratings) and a plurality of fibers used to carry light signals along a distance. More and more applications require the transmitter end to have optical signal monitoring structures to monitor the working status of the light emitting devices. For short reach optical systems, this is not an easy task to realize because the structure of the light emitting devices, e.g. vertical cavity surface emitting lasers (VCSELs), do not support back side light emitting, which prevents a convenient way to add optical monitors, such as monitoring photodetectors (mPDs). This becomes even more difficult when a much more compact packaging form factor standard QSFP+ is employed for 40G/100G applications due to the already very crowded space arrangement in the package.